1. Field
The present disclosure relates generally to communication systems, and more particularly, to system information acquisition in a connected mode.
2. Background
Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power). Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency divisional multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.
These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. An example of an emerging telecommunication standard is Long Term Evolution (LTE). LTE is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by Third Generation Partnership Project (3GPP). It is designed to better support mobile broadband Internet access by improving spectral efficiency, lower costs, improve services, make use of new spectrum, and better integrate with other open standards using OFDMA on the downlink (DL), SC-FDMA on the uplink (UL), and multiple-input multiple-output (MIMO) antenna technology. However, as the demand for mobile broadband access continues to increase, there exists a need for further improvements in LTE technology. Preferably, these improvements should be applicable to other multi-access technologies and the telecommunication standards that employ these technologies.
In LTE, the user equipment (UE) applies the system information acquisition procedure to acquire the access stratum (AS) and non-access stratum (NAS) system information that is broadcasted by the Evolved Universal Terrestrial Radio Access Network (E-UTRAN). The procedure applies to UEs in the RRC_IDLE state and UEs in the RRC_CONNECTED state. When a UE is in the RRC_CONNECTED state, the UE must ensure that it has a valid version of the MasterInformationBlock (MIB), SystemInformationBlockType1 (SIB1), SystemInformationBlockType2 (SIB2), and SystemInformationBlockType8 (SIB8 ) when CDMA2000 is supported. This minimal set of system information is sufficient for the UE to stay on the cell in the RRC_CONNECTED state. When the UE is in the RRC_IDLE state, the UE needs to ensure that it has a valid version of the MIB, SIB1 , SIB2, and SystemInformationBlockType3 (SIB3) through SystemInformationBlockType8 (SIB8 ). Acquiring the requisite system information for the RRC_IDLE state at the time of transitioning on the same cell from the RRC_CONNECTED state to the RRC_IDLE state can potentially cause an unnecessary delay that could lead to call failures and missed pages, as well as an increased likelihood of going out of service. As such, there is a need for an apparatus and a method for reducing the delay due to system information acquisition during a transition on the same cell between the RRC_CONNECTED state and the RRC_IDLE state.